1. Field of the Invention
Materials and devices consistent with the present invention relate to plated flat conductors and flexible flat cables therewith applied to electronic devices.
2. Description of the Related Art
Compact electronic devices such as mobile phones, digital cameras, CD players, ink-jet printers and the like require compact and flexible wiring means. Flexible flat cables are frequently used for such purposes. A flexible flat cable is generally provided with a plurality of flat conductors arranged in parallel and covered with thin insulator films. Ends of the flat conductors are led out of the insulator films, and these ends are applied to electrical connections. For the purpose of reduction of electrical contact resistance and/or improvement of quality of soldering, the flat conductors are often subject to tinning (plating with pure tin or any tin alloy).
Although it is desired to avoid the use of lead in view of environmental protection, tin and tin alloys free from lead are known to cause growth of a “crystal whisker” (or “whisker” in short, which is a single crystal grown in a filamentary form) therefrom during use after production. The whiskers can grow in a very long form (100 μm or longer, for example) relative to distances among conductors in such down-sized electronic devices. If whiskers grow from plated flat conductors embedded in a flexible flat cable, some problems, such as short circuits, for example, may occur.